The present invention relates to cockpit voice recorders and flight data recorders, and in particular to a downlink system for transmitting cockpit audio and critical flight data parameters to a satellite communications system upon detection of a serious event or detection of a pilot generated signal.
Larger aircraft are equipped with ground proximity warning devices (GPWS), such as that disclosed in U.S. Pat. No. 3,946,358, the complete disclosure of which is incorporated by reference herein. The GPWS devices process input received from an air data computer and radio altimeter found as separate discrete devices aboard the aircraft. The GPWS alerts the pilot to unsafe flight conditions such as proximity to terrain and illogical combinations of airspeed, altitude and aircraft configuration. Larger aircraft are also equipped with an additional discrete piece of hardware known as a flight data recorder (FDR), such as that disclosed in U.S. Pat. No. 5,508,922, U.S. Pat. No. 4,729,102 and U.S. Pat. No. 4,644,494, the complete disclosures of which are incorporated by reference herein, that further enhances the safety of flight operations. The flight data recorder, or xe2x80x9cblack boxxe2x80x9d, records various parameters, including the aircraft configuration, altitude and airspeed, received from multiple sensors located throughout the aircraft. Larger aircraft are further equipped with cockpit voice recorders (CVR), such as that disclosed in U.S. Pat. No. 5,627,753, the complete disclosure of which is incorporated by reference herein. The cockpit voice recorder provides an audio record of the cockpit activity during flight, including radio transmissions. The recorded cockpit audio and critical flight data is useful for determining the cause of accidents or for monitoring the performance of an aircraft pilot and crew as well as an individual aircraft and its component parts. The recorded data thus aids in accident prevention by identifying possible changes in flight operations, aircraft component design and maintenance that improve flight safety.
The ground proximity warning devices, flight data recorder, and cockpit voice recorders are designed for larger aircraft and are generally unsuitable for use in smaller general aviation airplanes. For example, the discrete analog circuitry of some GPWS devices and their associated power requirements are incompatible with the power supplies and space/weight limitations of smaller aircraft. In addition, GPWS devices processes input received from an air data computer and radio altimeter found as separate discrete devices aboard the aircraft. These discrete devices are unlikely to be found on smaller general aviation aircraft due to the additional space and weight required to house them. Furthermore, the complicated design and manufacture of these sophisticated devices makes their cost prohibitive to owners of smaller, general aviation airplanes.
The flight data recorder and its complicated array of sensors are also too bulky and expensive to be suitable for use on smaller aircraft. As described in U.S. Pat. No. 5,508,922, the complete disclosure of which is incorporated by reference herein, the survivability requirements placed on the flight data recorder crash survivable protective enclosure add to the cubic volume of the recorder. U.S. Pat. Nos. 5,123,538; 5,407,505 and 5,438,162, the complete disclosures of which are incorporated by reference herein, define large volume and weight necessary to satisfy the survivability requirements placed on the crash survivable protective enclosures. In addition to the survivability requirements placed on the flight data recorder housing, the size of the tape drive or disc and associated circuitry also adds to the cubic volume of the recorder. The power requirements of this circuitry is also incompatible with the power available on a smaller aircraft.
U.S. patent application Serial No. 08/599,735, entitled xe2x80x9cTerrain Warning Systemxe2x80x9d and filed on Feb. 12, 1996 in the names of Snyder, et al, the complete disclosure of which is incorporated by reference herein, discloses an alerting system of an appropriate size, weight and cost for general aviation aircraft. The disclosed flight safety device provides the pilot with alerts of various predetermined flight conditions, including terrain proximity warnings, altitude call-outs and improper gear/flap configuration. The disclosed flight safety device includes a flight data recorder for recording multiple aircraft data, including the aircraft altitude, and/or other aircraft data. The device is designed and sized such that it can be mounted as an integral unit in the instrument panel of the aircraft.
Other ground proximity warning devices, flight data recorder, and cockpit voice recorders are designed for use in rotary wing aircraft, such as helicopters. For example, each of U.S. Pat. No. 5,666,110 and U.S. patent application Ser. No. 08/844,116, entitled xe2x80x9cSystems and Methods for Generating Altitude Callouts for Rotary Wing Aircraftxe2x80x9d and filed on Apr. 29, 1997 in the names of Paterson, et al, the complete disclosures of which are incorporated by reference herein, disclose warning devices for receiving altitude and flight condition signals and indicating the aircraft altitude to the pilot. U.S. Pat. No. 5,383,133, the complete disclosure of which is incorporated by reference herein, discloses a system for providing vibration reduction and health monitoring for a rotary wing aircraft, the system collecting flight data from multiple on-board sensors into a diagnostic computer coupled to a flight control device that includes a provision for downloading the data to a ground station.
Although cockpit voice recorders and flight data recorders for larger aircraft are built to withstand extreme conditions that can occur during violent crashes, the cockpit voice recorder or flight data recorders recovered from some airplane crashes fail to record the critical last few minutes of the flight. One reason these devices failed to record voice or data information was a catastrophic disconnects of the information or power supplied to those devices. The flight data recorders used in smaller general aviation aircraft and rotary wing aircraft are smaller and less costly than those in larger aircraft and, as a result, are less likely to survive a crash. Another disadvantage of cockpit voice recorders and flight data recorders is that recovery can be delayed by the environment where the airplane crashed, such as the ocean.
There exists a need to be able to quickly receive voice and flight information of aircraft that have crashed. Also, there is a need to ensure that the voice and flight information is recorded to the very end of the flight.
U.S. Pat. No. 5,890,079 attempts to satisfy need by disclosing a system that replaces existing flight data recorders with a remote monitoring and recordation system. U.S. Pat. No. 5,890,079, the complete disclosure of which is incorporated by reference herein, discloses a system that monitors aircraft performance parameters and broadcasts the data, along with aircraft identification information, audio, video, global positioning and altitude data, to a world wide two-way radio frequency network for monitoring and recording at a remote, centralized location. The disclosed system fails to recognize the limited band width provided by state of the art airborne communications systems and the concomitant restriction on downlink data rate per channel. Although current satellite and ground station antennas are capable of receiving transmissions of all of the data stored on the flight data recorder and cockpit voice recorder, a communications system capable of downlinking so much data would require an antenna having a bandwidth matching that of the target communications satellite or ground station antenna. Such an antenna is not practical given the current state of the art of airborne communications devices. For example, an antenna having a bandwidth matching that of the communications satellite or ground station antenna would be impracticably large, for example, as large as the aircraft cross-section. Rather, state of the art airborne communication systems typically operate with a weight, size and cost-conscious low profile antenna. Thus, state of the art airborne communication systems typically provide only a 9600 baud rate transmission capability, which severely limits the amount of data that can be downlinked to a communications satellite or ground station. Each of U.S. Pat. No. 4,729,102 and U.S. Pat. No. 5,383,133 also provides means for downloading recorded flight data to a ground station, but each fails to recognize the restrictions placed on downlink capability by current state of the art airborne communications systems and attempts to download more data than the relatively slow datalink can accommodate in a reasonable period of time.
The period of time available for downloading data in critical situations depends upon the elapsed time between the first indications of a threatening event and the loss of transmission capability. Air crashes may occur several minutes to an hour or more after the threatening event, but may also occur within mere seconds. Critical data must be transmitted before the aircraft losses the ability to communicate. State-of-the-art flight data recorders and cockpit voice recorders are restricted to collecting and storing pre-selected voice and flight data for later analysis. What is needed is a means of ensuring that meaningful data is available in a ground-based repository for later analysis. Another need is a means of monitoring the available data and determining which data are critical and when to transmit that data, thereby ensuring that meaningful data is transmitted in a timely fashion.
The present invention overcomes the limitations of the prior art by providing a means of ensuring that meaningful data is available in a ground-based repository for later analysis. The present invention further overcomes the limitations of the prior art by providing a means of monitoring the available data and determining both which data are critical and when to transmit that data, thereby ensuring that meaningful data are transmitted in a timely fashion.
According to one aspect of the invention, a method is provided for transmitting voice and flight parameter data, the method including monitoring one or more flight parameters, determining the presence of an abnormal condition, and initiating a downlink of one or more cockpit audio data and flight data in response to determining an abnormal condition. Additionally, the method of the invention includes initiating a data downlink responsive to the activation of an event marker.
According to one aspect of the invention, the determining of an abnormal condition further includes determining one or more of several predetermined emergency conditions and/or one or more other serious events.
According to one aspect of the invention, the downlink is made using one or more on-board communications systems, such as a conventional telephone-based satellite communication system as well as any available radio data link, such as a high frequency (HF) data link, a very high frequency (VHF) data link, and an ultra high frequency (UHF) data link, to transmit the flight data parameters to a ground-based data storage center.
According to one aspect of the invention, the operability of each of on-board communications system is determined and the flight data are arranged into data packets for transmission as a function of which on-board communications systems are operable. Different ones of the data packets are assigned to different ones of the operable on-board communications systems.
According to yet another aspect of the invention, the invention provides an airborne distress link device embodying the above method. The device is configured either as a stand-alone unit or as a component of another avionics device, i.e., as an algorithm operating on a processor embedded in another avionics device having access to the triggering signals and sufficient processing capacity to operate the algorithm in addition to the device""s normal function.